New York
Toxic algae in Rensselaer County lakes
13 lakes and waterways in Rensselaer County have harmful algal bloom reports in New York's official data. The most recent entry is for Tomhannock Reservoir: Tomhannock Reservoir was on New York's harmful algal bloom list on 4 October 2025, with confirmed bloom status (1 report). Tomhannock Reservoir, Burden Lake and Vosburg Pond and 2 more have had blooms in three or more years.
Lakes with bloom history
Newest report first. Each lake has its own page with the full history and what the results mean.
Other waterbodies with a report
These have one or two reports in a single year, which isn't enough history for a page of their own yet.
- Dunham Reservoir 2025
- Glass Lake 2021
- Moordener Kill 2022
- Reichards Lake 2025
- Troy Reservoir 2018
- Valatie Kill 2014
Source: New York State Department of Environmental Conservation (DEC), official data, checked 24 October 2026. For today's conditions see the NYHABS map. No report doesn't mean a lake is safe: most water is only tested occasionally.